Model releaseModerate global significanceConfirmed confidence
Anthropic releases Claude Sonnet 4.5
Anthropic released Claude Sonnet 4.5 with gains in coding, complex agents, computer use, reasoning, and math.
What happened
Event details
Claude Sonnet 4.5 focuses on stronger coding, complex agentic workflows, computer use, reasoning, and math. Anthropic released the closed-source model on September 29, 2025; the parameter count is undisclosed and it is an autoregressive Transformer. The primary source is "Introducing Claude Sonnet 4.5."
Assessment
Why it matters
Rated on the impact-v1 six-axis scale: technical 3/5, market 2/5, ecosystem 2/5, policy & social 1/5, scope 3/5, durability 3/5.
58/100Global significance score. Regional effects are recorded only when the evidence supports a meaningful difference.